Even the best and most sophisticated conservation equipment and supplies can count for naught if there are basic flaws in the way the material is handled, especially as there will be a need to handle the original artefacts for a whole variety of reasons, from aesthetic appreciation through educational enlightenment to scientific analysis.
The first step must be to survey the range of photographic material the archives hold. This may not even need to be done by direct examination; if the collection is documented or its provenance well recorded then direct handling can be avoided. A specific set of procedures can then be defined and tailored to the needs of the collection. This can then be communicated to staff and patrons alike by means of training sessions.
Usually a set of procedures will have to be drawn up to cover every eventuality and kind of material, as follows:
- Work only in designated areas e.g. the preservation suite
- Eating, drinking and smoking must be prohibited in this area
- Gloves or cots must always be used when handling photographic images and the surface of the image should never be touched by bare hand, ruler, or other object
- Always use the correct tools to pick up an image and always hold or support the image/matte in both hands
- Outsized, large, delicate or damaged images should always be cradled by an auxiliary support
- Always keep photographs face up and handle them one at a time
- Stack photographs carefully and never slide them from one stack to another; to remove any interleaving tissue, lift the photograph up and remove it; never drag it across the photograph
- Never stack glass plates on top of each other and for envelopes containing cracked plates always follow the guidelines listed below
- Never try to force two photographs apart
- Never allow pens or markers into the work space, only 2B pencils
Examination: general techniques
Essentially, there are three types of photographic examination: visual, by specialized equipment or by spot testing. A visual examination may further be broken down into assessment of handlability: can the image be picked up and viewed or not? Visual examination can be effected without actually handling the image, and there are techniques which allow this, but generally speaking it is much better, if the image is not in too fragile a state and is portable, to handle it.
Specialised examination techniques involve the use of sophisticated infra-red and ultra-violet spectroscopy, and X-ray fluoroscopy instruments. These are mainly applied by professionals, usually scientists in the field of conservation, and because most institutions are unable to afford such equipment and are unlikely to use it on a regular basis anyway. Their existence is, however, noteworthy when wishing to determine fungal or mould growth on organic binders, such as gelatin, and changes in metallic elements within the image layer.
Spot-testing involves a ‘sampling’ of part of the image which could damage the integrity of the artefact. Essentially this is a form of destructive testing and should only be performed under strictly controlled conditions, usually in a laboratory by a conservator under the supervision of a curator.
This is the simplest and most common of the identification methods and is achieved either by viewing with the naked eye or with the help of magnification equipment. The main aim of this level of scrutiny is to identify the content and surface of the image, and assess the extent of deterioration. Illumination of the image plays an important part and a range of light sources is essential for effective results. The sources should ideally be a variable mixture of incandescent (e.g. fibre optic) fluorescent and natural light. By virtue of their spectroscopic properties these offer variance in colour and intensity, and by viewing the image alternately under these sources, an appreciation of contrast may be achieved.
The angle and intensity of light is also of critical importance if the relief features of the image are to be fully assessed and appreciated. Therefore the optimum condition for illuminating the surface of the image is under low oblique or ‘raking’ light. This angle of approach reveals much about the texture of the surface and any physical damage (e.g. scratches, abrasions) which could have a deleterious effect on it. These sources must also be of similar intensity otherwise this could hamper or confuse the signals the brain receives via the eye.
Of course, the naked eye only has a limited level of resolution and, in order to resolve finer detail, magnification equipment is required. Improved resolution may be achieved either by use of a magnifying glass. The magnifying glass should be hand-held and internally lit.
Surface glasses should not be used because of the risk of abrasion, although this problem could be resolved by placing a polyacetate sheet (e.g. Secol, Melanex) over the surface of the image. This could however affect the ‘reading’ of the surface.
A higher level of magnification could be achieved by use of a stereomicroscope. Power of resolution is greater and the surface can be examined in greater depth to reveal internal problems and defects. Most modern stereomicroscopes have a camera attachment which will allow photographic recording of these defects for further scrutiny.